Modern electronic devices such as computers and mobile phones are developed with advancement of technology and have central process units (CPUs) thereof to be more efficient in arithmetic calculation, thereby producing more heat during operation of the electronic devices and making heat dissipation or temperature control more significantly concerned for the electronic devices. For example, it is critical to prevent electromigration effect that is induced by temperature rising above a threshold and causes a malfunction or breakdown of the electronic devices. Besides, heat dissipation plays an important role in system stability of CPUs in computers or other electronic devices; therefore, one main problem to be solved is to enhance heat dissipating efficiency in order to improve system performance.
For solving ventilation, convection and heat dissipation problems in computers, electrical and mechanical apparatuses, power suppliers, air-conditioning devices and other industrial appliances, it is general to install heat dissipating devices such as axial fans, centrifugal fans and other fans to direct airflow into a particular passage and to thereby dissipate the airflow together with heat generated from the electronic devices to the outside or atmosphere, so as to achieve heat dissipation and ventilation purposes.
As shown in FIGS. 7A and 7B that respectively illustrate a side view of a conventional electronic device for heat dissipation or air conditioning, a first fan 101 and a second fan 103 are mounted in a passage of the electronic device and used to exhaust air in the passage via air outlets 105, 107.
As shown in FIG. 7A, when the first fan 101 and the second fan 103 both operate normally, they can direct air in the passage to be exhausted via the air outlets 105, 107.
However, in the case of a breakdown of any one of the two fans, for example, the second fan 103 failing to operate properly and only the first fan 101 functioning normally, air can freely pass through the air outlet 107 that is connected to the second fan 103, which may cause reverse airflow as indicated by dotted arrows in FIG. 7B. Besides the reverse airflow, it also seriously affects exhaust of inner air in the passage or even affects operation of the first fan 101, making heat dissipating efficiency of the electronic device undesirably reduced; this problem would be more sever in an electronic device with an advanced CPU that is in high demand of heat dissipation.
In response to the above heat dissipation problem induced by malfunctioning of a heat dissipating mechanism of the electronic device, a solution is to install a compensation mechanism for improving power of the heat dissipating mechanism; that is, if one of the fans fails to function properly, the compensation mechanism operates to elevate power of the other normally-functioning fans to maintain heat dissipating efficiency of the heat dissipating mechanism by means of forced convection for exhaust or convection of inner air in the electronic device.
However, provision of the compensation mechanism would increases fabrication costs and structural complexity; as it needs to take a period of time for the compensation mechanism to detect and react to malfunctioning of the fan, the electronic device may be broken down due to high temperature before an action or response is made by the compensation mechanism.
Moreover, as the fans are directly connected with air inlets or air outlets, reverse airflow occurs in a breakdown of the malfunctioning fan and also affects operation of other normally-functioning fans by which efficiency of convection or heat dissipation is significantly reduced, thus increasing load of the compensation mechanism and making the compensation mechanism easily damaged.
Therefore, the problem to be solved herein is to provide a flow direction control mechanism that can solve the foregoing drawbacks without significantly increasing fabrication costs.